This application relates to the art of controls and, more particularly, to manually operable single controls that perform multiple functions. The invention is particularly applicable for use with airless paint sprayers and will be described with specific reference thereto. However, it will be appreciated that the invention has broader aspects and that certain features of the invention can be used for other purposes.
Airless paint sprayers typically have an on/off switch, a bypass valve for priming and pressure relief, and a pressure adjusting valve for adjusting the pressure at which paint is supplied to the spray gun so that the pressure is suitable for the project at hand.
It is common to have a separate manually operable control for each of the on/off switch, the bypass valve and the pressure adjusting valve. A typically recommended operating procedure advises a user to first move the pressure adjusting control to the low pressure position and the bypass valve control to the open or prime position before the switch is turned on. After the switch is turned on by operating the switch control, the user must move the separate pressure adjusting control to a medium pressure setting and wait for the unit to prime. Once the unit is primed, the user must move the separate bypass valve control to the spray position and move the separate pressure adjusting control to the desired pressure setting before spraying can begin.
In devices of the type described, a user does not know the pressure setting of the pressure adjusting valve unless the sprayer has an attached pressure gauge. In addition, arrangements of the type described permit a user to turn the switch to its off position while leaving the unit at fill pressure. This is undesirable because a user may try to remove a hose or misdirect spray by not realizing that the unit remains under pressure even though it is turned off.
An arrangement has been proposed that will not allow a user to shut the sprayer off while it is under pressure but it includes two separate controls that are arranged to force a user to operate them in a certain order.
It would be desirable to have a simplified control arrangement that operates in a predetermined sequence and avoids problems associated with existing arrangements.